The present invention relates to planning and acquisition of computed tomography (CT) scans of a target organ, and more particularly, to planning and acquisition of dose-optimized CT lung scans.
Computed tomography (CT) is a medical imaging technique that makes use of computer-processed combinations of many X-ray projection images taken from different angles to produce cross-sectional images of specific areas of a scanned object. CT can be used to generate a three-dimensional (3D) image of the inside of the scanned object from a series of two-dimensional projection images taken around a single axis of rotation. CT chest or lung scans can be used for detecting both acute and chronic changes in the lung parenchyma. For example, because CT is able to detect very small nodules in the lung, CT lung scans are often used for diagnosing lung cancer at its earliest, most curable stage.
CT scans expose patients to radiation, which can be harmful. Lung scans currently require topographic scans of the patient previous to the actual acquisition of the diagnostic CT lung scan. Such a topographic scan is used to obtain a topogram, which is a scout image obtained with a low dose of radiation at a low resolution that is used for planning the high-dose diagnostic scan. The topogram is typically a whole body flat sagittal section, obtained with the CT gantry stopped and the X-ray tube fixed at the upper position. Using the topogram, a series of manual steps is used to plan the scan range of the diagnostic CT lung scan to attempt to limit the exposure of the tissue beyond the lung to as little x-ray radiation dose as possible in the subsequent diagnostic CT scan. However, techniques to further limit the radiation dose that patients are exposed to during CT lung scans are desirable.